In human brains, the earliest structure, the reptilian brain, is mostly focused on the survival of the organism, controlling muscles, balance and autonomic functions. It is covered by the limbic brain, which records experience to create emotion and facilitates learning. Finally, the overlying neocortex is responsible for human culture, allowing the development of language and abstract thought.

Artificial intelligence engineer Christopher MacLeod and his colleagues at the Robert Gordon University in Aberdeen, UK, have arranged for the robot to evolve in hours. It accomplishes in this short time what animals have done over hundreds of millions of years.

The team started with a simple robot the size of a paperback book, with two rotatable pegs for legs that could be turned by motors through 180 degrees. They then gave the robot's six-neuron control system its primary command - to travel as far as possible in 1000 seconds. The software then set to work evolving the fastest form of locomotion to fulfil this task.

"It fell over mostly, in a puppyish kind of way," says MacLeod. "But then it started moving forward and not falling over straight away - and then it got better and better until it could eventually hop along the bench like a mudskipper."

When the IEA realises that its evolutions are no longer improving the robot's speed it freezes the neural network it has evolved, denying it the ability to evolve further. That network knows how to work the peg legs - and it will continue to do so.

At this point, it is just like any other evolved robot: it would be unable to cope with the addition of knee-like joints, say, or more legs. But unlike conventional EAs, the IEA is sensitive to a sudden inability to live up to its primary command. So when the team fixed jointed legs to their robot's pegs, the software "realises" that it has to learn how to walk all over again. To do this, it automatically assigns itself fresh neurons to learn how to control its new legs.

This innocent tale of machine evolution reminds me of a somewhat darker version provided by Philip K. Dick in his 1953 short story Second Variety:

"Interesting, isn't it?"

"What?"

"This, the new types. The new varieties of claws. We're completely at their mercy, aren't we? By now they've probably gotten into the UN lines, too. It makes me wonder if we're not seeing the beginning of a new species. The new species. Evolution. The race to come after man." (Read more about Dick's claws)

Update: See also the Vulcan 3 computer from Dick's 1960 novel Vulcan's Hammer for an example of a large computer system that modifies itself extensively. End update.